Then certain of the vagabond Jews, exorcists, took upon them to call over them which had evil spirits the name of the Lord Jesus, saying, We adjure you by Jesus whom Paul preacheth. And there were seven sons of one Sceva, a Jew, and chief of the priests, which did so. And the evil spirit answered and said, Jesus I know, and Paul I know; but who are ye?

I suppose that here we have a warning not to try and exercise a God-given vocation which we have not, in fact, been given. Jesus is the second person of the Trinity, so depicted in the above passage is a behaviour which is in direct contravention the third commandment:

“Thou shalt not take the name of the Lord thy God in vain: for the Lord will not hold him guiltless that taketh his name in vain.”

The sons of Sceva discovered to there cost that God will punish any attempt to glorify self, which presumes upon his name.